1. Field of the Invention
This invention is directed to a parking meter structure and particularly a cancelling device for cancelling the parking meter upon departure of the vehicle from the controlled space.
2. Description of the Prior Art
Since their inception and initiation of use as devices in association with parking spaces, parking meters have evolved. A number of structural concepts have been tested, and the meter in general use today is one of particular style manufactured by the Duncan Company. One of the advantages of the Duncan meter over some of the previous designs includes the concept that the user inserts a coin and turns a crank to wind the spring motor-driven timer. A signal hand on the timer indicates the amount of time left on the meter before the timer times out and the violation sign shows.
During the development of the meter structure, there also evolved the purpose of the meter use. As originally conceived, the parking meter was created in order to control parking spaces; i.e., charge for the use of parking space on the basis of time to thus urge those people who plan to park for a longer time to find a place away from the center of activity. From this original purpose of the parking meter, there also evolved function of raising money for the municipality which owns and operates the parking meter. In such situations, an effective cancelling device would produce much additional revenue.
The ordinary parking meter which does not have any way of detecting the presence of a vehicle in the adjacent controlled space must necessarily return to the violation state in which there is no time on the meter only by timing out. Since the meter is the means for raising revenue for the municipality, it is apparent that the revenue will be substantially increased if the parking meter is returned to its "zero" setting when the parking space is vacated so that the next motorist is compelled to pay the usual parking fee.
Parking meter cancelling devices have been the subject of much study and design work. A number of attempts have been made to create a feasible, universal, and functional device, but they have failed to produce a unit which satisfies enough of the requirements in order to be economically useful. Some of the requirements which are based on the economics of the parking meter include the requirement that the design involve a minimum number of working parts, and that it be a structure which is extremely rugged and independent of the outdoor temperature excursions. Additionally, the unit should utilize the latest design in order to avoid premature obsolescence. Of course, the unit should be incorporatible into existing designs and preferably by adaptable for addition to existing installed meters. Above all, the unit must be able to discriminate between parked cars and the movement of passing objects, automobiles, and pedestrians so that it actuates only when the vehicle is driven out of the controlled parking space and is not subject to actuation by spurious signals.